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1.
Nano Lett ; 23(18): 8753-8760, 2023 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-37712849

RESUMEN

X-ray dose detection plays a critical role in various scientific fields, including chemistry, materials, and medicine. However, the current materials used for this purpose face challenges in both immediate and delayed radiation detections. Here, we present a visual X-ray dosimetry method for multienvironment applications, utilizing NaLuF4 nanocrystals (NCs) that undergo a color change from green to red upon X-ray irradiation. By adjustment of the concentrations of Ho3+, the emission color of the NCs can be tuned thanks to the cross-relaxation effects. Furthermore, X-ray irradiation induces generation of trapping centers in NaLuF4:Ho3+ NCs, endowing the generation of mechanoluminescence (ML) behavior upon mechanical stimulation after X-ray irradiation ceases. The ML intensity shows a linear correlation with the X-ray dose, facilitating the detection of delayed radiation. This breakthrough facilitates X-ray dose inspection in flaw detection, nuclear medicine, customs, and civil protection, thereby enhancing opportunities for radiation monitoring and control.

2.
Phys Chem Chem Phys ; 24(43): 26477-26484, 2022 Nov 09.
Artículo en Inglés | MEDLINE | ID: mdl-36300484

RESUMEN

Two-dimensional magnetic van der Waals materials provide a fertile platform for the design and control of topological spin textures such as skyrmions. However, despite studies reporting skyrmions in many 2D magnetic systems, those of the hosting van der Waals materials remain limited. Here, via first-principles calculations and Monte Carlo simulations, we propose BiCrX3 as a new family of materials for hosting skyrmions. Due to the large SOC of the X atom and intrinsic inversion asymmetry, an inherent large DMI occurs in all systems, enabling intriguing Néel-type skyrmions. Furthermore, upon applying a moderate magnetic field, isolated skyrmions and skyrmion lattices emerge in our systems, and are robust within a relatively wide temperature range.

3.
Phys Chem Chem Phys ; 21(36): 19963-19968, 2019 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-31478037

RESUMEN

Six new silicon phases with direct band gaps were found through silicon atomic substitution of carbon in the known carbon structures via high-throughput calculations. The six newly discovered Si phases are in the space groups of Im3[combining macron]m, C2/c, I4/mcm, I4/mmm, P21/m, and P4/mbm, respectively. Their crystal structures, stabilities, mechanical properties, elastic anisotropy, and electronic and optical properties were systematically studied using first-principles density functional theory calculations. All the new phases were proved to be thermodynamically and mechanically stable at ambient pressure. The direct band gap values in the range of 0.658-1.470 eV and the excellent optoelectronic properties of these six Si allotropes suggest that they are promising photovoltaic materials compared to diamond silicon.

4.
Gynecol Endocrinol ; 34(4): 332-335, 2018 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-29166799

RESUMEN

This study was aimed to investigate the attitudes and knowledge of medical personnel on hormone replacement therapy (HRT) in treating perimenopausal syndrome. A total of 2580 self-administered questionnaire forms were sent to medical care professionals and the responses collected were anonymous. The questionnaire included information on levels of awareness, benefits, and potential risks of HRT. A total of 2158 questionnaire forms were filled and used for statistical analysis; 61.4% of gynecologists believed that it was necessary to conduct HRT in suitable patients, 89.1% would like to recommend the therapy to patients with perimenopausal syndrome, and 83.2% of the participants were willing to take training on HRT. The mean score of awareness of HRT among the respondents was 3.14 out of 10. The main reason for them to avoid HRT was fear of cancer (43.8%), weight gain (30.4%), addiction (21.9%), and thrombus (3.9%). These results indicated that a large proportion of gynecologists are willing to recommend HRT to a woman complaining of climacteric disorders. However, awareness of HRT among the health workers (including gynecologists) is relatively low. They are also worried about the risks. A more concerted effort should be made to better disseminate information on HRT.


Asunto(s)
Conocimientos, Actitudes y Práctica en Salud , Personal de Salud , Terapia de Reemplazo de Hormonas , Adolescente , Adulto , Anciano , Actitud del Personal de Salud , China , Encuestas de Atención de la Salud , Humanos , Persona de Mediana Edad , Pautas de la Práctica en Medicina , Adulto Joven
5.
Neural Plast ; 2017: 3192090, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-28695016

RESUMEN

Hereditary hearing loss is characterized by a high degree of genetic heterogeneity. Mutations in the TMPRSS3 (transmembrane protease, serine 3) gene cause prelingual (DFNB10) or postlingual (DFNB8) deafness. In our previous study, three pathogenic mutations in TMPRSS3 were identified in one Chinese family. To evaluate the importance of TMPRSS3 mutations in recessive deafness among the Chinese, we screened 150 autosomal recessive nonsyndromic hearing loss (ARNSHL) families and identified 6 that carried seven causative TMPRSS3 mutations, including five novel mutations (c.809T>A, c.1151T>G, c.1204G>A, c.1244T>C, and c.1250G>A) and two previously reported mutations (c.323-6G>A and c.916G>A). Each of the five novel mutations was classified as severe, by both age of onset and severity of hearing loss. Together with our previous study, six families were found to share one pathogenic mutation (c.916G>A, p.Ala306Thr). To determine whether this mutation arose from a common ancestor, we analyzed six short tandem repeat (STR) markers spanning the TMPRSS3 gene. In four families, we observed linkage disequilibrium between p.Ala306Thr and STR markers. Our results indicate that mutations in TMPRSS3 account for about 4.6% (7/151) of Chinese ARNSHL cases lacking mutations in SLC26A4 or GJB2 and that the recurrent TMPRSS3 mutation p.Ala306Thr is likely to be a founder mutation.


Asunto(s)
Pérdida Auditiva Sensorineural/genética , Proteínas de la Membrana/genética , Mutación , Proteínas de Neoplasias/genética , Serina Endopeptidasas/genética , Adulto , Edad de Inicio , Niño , Preescolar , China , Análisis Mutacional de ADN , Femenino , Pérdida Auditiva Sensorineural/diagnóstico , Humanos , Recién Nacido , Masculino , Índice de Severidad de la Enfermedad , Adulto Joven
6.
Zhonghua Fu Chan Ke Za Zhi ; 50(5): 352-5, 2015 May.
Artículo en Zh | MEDLINE | ID: mdl-26311454

RESUMEN

OBJECTIVE: To explore the serum anti-Mullerian hormone (AMH) level in women of childbearing age with normal menstrual cycles. METHODS: A total of 1 423 women with regular menstrual cycles were selected and divided into 5 groups according to their ages, i.e. ≤ 25, 26-30, 31-35, 36-40, ≥ 41 years. Their serum levels of AMH were measured, and the relationship between AMH and age was analyzed. RESULTS: The serum AMH levels of 5 groups according to ages (≤ 25, 26-30, 31-35, 36-40, ≥ 41 years) were 3.62, 3.10, 2.27, 1.07, 0.45 µg/L, respectively. The comparison of serum AMH levels in different age groups had significant difference (P < 0.01). Serum AMH level declined with increasing age, and dropped significantly after 36. The serum AMH level and age showed a negative correlation with significant difference (r = -0.374, P < 0.01). Quadratic regression of logAMH proximally reflected the relationship between AMH and age. CONCLUSION: AMH determination for women of childbearing age could provide reference for the evaluation of ovarian function.


Asunto(s)
Envejecimiento/fisiología , Hormona Antimülleriana/sangre , Ovario/fisiología , Adulto , Biomarcadores/metabolismo , Femenino , Humanos , Ciclo Menstrual
7.
J Chem Phys ; 139(16): 164710, 2013 Oct 28.
Artículo en Inglés | MEDLINE | ID: mdl-24182067

RESUMEN

Additional electrons can drastically change the bonding trend of light elements. For example, N atoms in alkali metal azides form the linear N3(-) anions instead of N2 molecules with the introduction of additional electrons. The effect of the additional electrons on the polymerization of N under pressure is important and thus far unclear. Using first principles density functional methods and the particle swarm optimization structure search algorithm, we systematically study the evolution of LiN3 structures under pressures up to 600 GPa. A stable structure featuring polymerized N under pressures higher than 375 GPa is identified for the first time. It consists of zig-zag N polymer chains that are formed by N5(-) five-member rings sharing N-N pairs. Throughout the stable pressure range, the structure is insulating and consists of N atoms in sp(3) hybridizations. Comparing with the atomic and electronic structures of previous phases, our study completes the structural evolution of LiN3 under pressure and reveals the structural changes which are accompanied and driven by the change of atomic orbital hybridization, first from sp to sp(2) and then from sp(2) to sp(3).

8.
Medicine (Baltimore) ; 102(20): e33779, 2023 May 19.
Artículo en Inglés | MEDLINE | ID: mdl-37335711

RESUMEN

BACKGROUND: Gastroesophageal reflux-related chronic cough (GERC), is one common type of chronic cough. Drug treatment is effective for some GERC patients. But, there is refractory GERC (rGERC). For rGERC, fundoplication may be the only effective method. However, there were very few studies about laparoscopic fundoplication in treating rGERC, and the cure rate of fundoplication in treating rGERC was unknown. So there is a question, what is the cure rate of fundoplication in treating rGERC? To solve this question, we performed this meta-analysis. METHODS: The PRISMA strategy and Cochrane collaboration method were used for this study. Our study was registered with PROSPERO (ID: CRD42021251072). We searched PubMed, Medline, Web of Science, and the Cochrane databases from 1990 to December 2022. The meta-analysis was performed with Review Manager 5.4 and Stata 14. RESULTS: After selection and exclusion, 8 articles out of 672 were included. The meta-analysis showed the cure rate of laparoscopic fundoplication in treating rGERC was 62% (95% confidence interval: 53-71%), with no deaths in 503 patients. There was no significant heterogeneity or bias in the meta-analysis. CONCLUSIONS: In terms of safety, laparoscopic fundoplication is quite reliable offered by skilled surgeons. In terms of cure rate, laparoscopic fundoplication could completely heal two-thirds of rGERC patients; however, there are still some patients who can not be completely cured by fundoplication.


Asunto(s)
Reflujo Gastroesofágico , Laparoscopía , Humanos , Fundoplicación/métodos , Tos/etiología , Tos/cirugía , Laparoscopía/métodos , Reflujo Gastroesofágico/complicaciones , Reflujo Gastroesofágico/cirugía , Enfermedad Crónica , Resultado del Tratamiento
9.
Dalton Trans ; 50(12): 4159-4166, 2021 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-33666609

RESUMEN

There is an urgent need to develop phosphors with high quantum efficiencies (QEs) since white light-emitting diodes (WLEDs) have emerged as a new generation of illumination materials. Utilizing energy transfer to improve the absorption of activators and adjust the emission colors of samples is one effective strategy. Here, color-tunable phosphors of the form CaAl4O7:Ce,Tb were synthesized aiming at efficient energy transfer from Ce3+ to Tb3+. Since Tb3+ can be suitably sensitized by Ce3+, the co-doped phosphors can be effectively excited by near-ultraviolet (NUV) light. The internal QE of CaAl4O7:0.04Ce,0.04Tb under 350 nm excitation is as high as 92.55%, and the external QE is 71.02%. A WLED fabricated from BAM:Eu2+, CaAl4O7:0.04Ce,0.04Tb, and CaAlSiN3:Eu2+ with a 365 nm LED chip exhibited a correlated color temperature (CCT) of 4706 K and a color rendering index (CRI, Ra) of 81.44. The energy transfer mechanism and thermal stability of the phosphor were also investigated. The results provide an effective approach for developing highly efficient green-emitting phosphors for NUV WLEDs.

10.
Hear Res ; 401: 108161, 2021 03 01.
Artículo en Inglés | MEDLINE | ID: mdl-33422722

RESUMEN

Hair cells can be regenerated after damage by transdifferentiation in which a supporting cell directly differentiates into a hair cell without mitosis. However, such regeneration is at the cost of exhausting the support cells in the mammalian mature cochlea. Thus, more effective methods should be found to promote mitotic regeneration but partially preserve support cells after damage. To address the issue, we first injured hair cells in the chick basilar papillae (BP) by treatment with streptomycin in vitro. We then compared the mitotic regeneration on the neural side in the middle part of BP after treatment with a pharmacological inhibitor or agonist of the Notch (DAPT), Wnt (LiCl), Bmp (Noggin) or Fgf (SU5402) signaling pathway, with that after treatment with combinations of two or three inhibitors or agonist of these pathways. Our results indicate that treatments with a single inhibitor or agonist of the Notch, Wnt, Bmp or Fgf signaling pathway could significantly increase mitotic regeneration as well as direct transdifferentiation. The results also show that hair cells (Myosin 7a+), support cells (Sox2+) and mitotically regenerated hair cells (Myosin 7a+/Sox2+/BrdU+) increased significantly on the neural side in the middle part of BP after two or three combinations of the inhibition of Notch, Bmp or Fgf signaling pathway or the activation of Wnt signaling pathway, besides the reported coregulatory effects of Notch and Wnt signaling. The study of the effects of systematic combinations of pathway modulators provided more insight into hair cell regeneration from mitosis.


Asunto(s)
Órgano Espiral , Animales , Proliferación Celular , Pollos , Miosinas , Regeneración , Estreptomicina/toxicidad , Vía de Señalización Wnt
11.
Inorg Chem ; 49(15): 6859-64, 2010 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-20578702

RESUMEN

We have extensively explored the high-pressure structures of transition-metal diborides (TMB(2), TM = Sc, Ti, Y, and Zr) stabilized with the AlB(2)-type structure at ambient pressure by using first-principles structural prediction. We find two novel high-pressure structures: (i) a monoclinic structure (C2/m, Z = 4) for ScB(2) and YB(2) stable above 208 and 163 GPa, respectively; and (ii) a tetragonal alpha-ThSi(2)-type phase (I4(1)/amd, Z = 4) for TiB(2) stable above 215 GPa. Our calculations show that the electron transfer from transition-metals TM to B under pressure might be the main cause for the structural phase transitions. Further phonon and hardness calculations suggest that alpha-ThSi(2) phase of TiB(2) is quenchable to ambient pressure and possesses excellent mechanical property with a Vickers hardness of 29.8 GPa. Interestingly, ZrB(2) is quite stable and persists on the ambient-pressure AlB(2)-type structure up to at least 300 GPa. We attribute the strong covalent hybridization between the transition-metal Zr and B to this ultrastability.

12.
J Phys Condens Matter ; 32(38): 385404, 2020 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-32434173

RESUMEN

The pressure-induced structural phase transitions of halogen compound IF under high pressure were studied by using the unbiased CALYPSO structure prediction method. The phase transition sequence of IF under high pressure is determined to be P1 → P21/c-I → P21/c-II → I4/mmm, and the corresponding phase transition pressures are 3 GPa, 16.5 GPa and 46 GPa, respectively. The physical properties of each predicted phase were thus fully studied, and it was found that the P1 phase was unstable which is in excellent agreement with the experiment result. Furthermore, our exploration of the high pressure phases for IF will provide fundamental insights for further exploration the structural phase transition of other halogen compounds under high pressure.

13.
Sci Rep ; 9(1): 10494, 2019 07 19.
Artículo en Inglés | MEDLINE | ID: mdl-31324869

RESUMEN

There is a strong capacity for hair cell regeneration after damage in the inner ear of non-mammals. However, mammalian hair cells are substantially unable to regenerate. To obtain insights into the mechanism of this difference, we analyzed the transcriptomic changes in the mouse cochleae suffered from gentamicin damage and compared them with those in the chick cochleae suffered from the same damage. The results indicated that 2,230 genes had significantly differential expression between the gentamicin- and saline-treated mouse cochleae. Some of the differentially expressed genes were grouped into 265 signaling pathways, including the Notch, Wnt (Wingless and INT-1), Bmp (bone morphogenetic protein), FGF (fibroblast growth factor) and Shh (sonic hedgehog) pathways. Using pharmacological inhibitors or agonists of these pathways, the effects of these pathways on hair cell regeneration were further studied. The results indicated that Bmp alone and its coregulation with the Notch or Wnt signaling pathways increased the numbers of generated cells from transdifferentiation or proliferation in the mouse cochlea after damage, in addition to the reported coregulation of Notch and Wnt. Thus, this work indicates a new signaling pathway (Bmp) and its synergetic coregulation in mammalian hair cell regeneration, providing potential therapeutic targets to increase mammalian hair cell regeneration.


Asunto(s)
Cóclea/efectos de los fármacos , Gentamicinas/toxicidad , Células Ciliadas Auditivas/metabolismo , Transducción de Señal , Animales , Pollos , Cóclea/metabolismo , Perfilación de la Expresión Génica , Ratones , Reacción en Cadena en Tiempo Real de la Polimerasa , Regeneración
14.
Nanoscale ; 10(36): 17335-17340, 2018 Sep 20.
Artículo en Inglés | MEDLINE | ID: mdl-30198045

RESUMEN

Design of novel two-dimensional (2D) magnetic materials with large magnetic anisotropy energy (MAE) is highly desirable for nanoscale magnetic devices. Through systematic first-principles calculations, we found a huge MAE up to 180 meV in a 2D Ir-dicyanoanthracene (Ir-DCA) framework with the easy axis perpendicular to the sheet. Analysis of the electronic structures reveals that the ultra large MAE originates from the coupling between the spin down dxy and dx2-y2 orbitals in the minority spin channel. Moreover, the perpendicular MAE can be further enhanced to 220 meV by applying an external tensile biaxial strain (∼3%). Finally, our calculations indicate that the unique magnetic properties of Ir-DCA can be retained when supported on a hexagonal boron nitride (h-BN) substrate. These features make the Ir-DCA framework a promising candidate for potential applications in spintronic devices at high temperatures.

15.
Materials (Basel) ; 11(1)2018 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-29320470

RESUMEN

Using an unbiased structure searching method, a new orthorhombic Cmmm structure consisting of ZrIr12 polyhedron building blocks is predicted to be the thermodynamic ground-state of stoichiometric intermetallic Ir2Zr in Ir-Zr systems. The formation enthalpy of the Cmmm structure is considerably lower than that of the previously synthesized Cu2Mg-type phase, by ~107 meV/atom, as demonstrated by the calculation of formation enthalpy. Meanwhile, the phonon dispersion calculations further confirmed the dynamical stability of Cmmm phase under ambient conditions. The mechanical properties, including elastic stability, rigidity, and incompressibility, as well as the elastic anisotropy of Cmmm-Ir2Zr intermetallic, have thus been fully determined. It is found that the predicted Cmmm phase exhibits nearly elastic isotropic and great resistance to shear deformations within the (100) crystal plane. Evidence of atomic bonding related to the structural stability for Ir2Zr were manifested by calculations of the electronic structures.

16.
Hear Res ; 361: 66-79, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29395614

RESUMEN

Unlike mammalian hair cells, which are essentially unable to regenerate after damage, avian hair cells have a robust capacity for regeneration. The prerequisite for understanding the above difference is knowing the genetic programming of avian hair cell regeneration. Although the major processes have been known, the precise molecular signaling that induces regeneration remains unclear. To address this issue, we performed a high-throughput transcriptomic analysis of gene expression during hair cell regeneration in the chick cochlea after antibiotic injury in vivo. A total of 16,588 genes were found to be expressed in the cochlea, of which about 1000 genes were differentially expressed among the four groups studied, i.e., 2 days (d) or 3 d post-treatment with gentamicin or physiological saline. The differentially expressed genes were distributed across approximately one hundred signaling pathways, including the Notch, MAPK (FGF), Wnt and TGF-ß (BMP) pathways that have been shown to play important roles in embryonic development. Some differentially expressed genes (2-3 in each pathway) were further verified by qRT-PCR. After blocking Notch, FGF or BMP signaling, the number of regenerating hair cells and mitotic supporting cells increased. However, the opposite effect was observed after suppressing the Wnt pathway or enhancing BMP signaling. To our knowledge, the present study provided a relatively complete dataset of candidate genes and signaling pathways most likely involved in hair cell regeneration and should be a useful start in deciphering the genetic circuitry for inducing hair cell regeneration in the chick cochlea.


Asunto(s)
Proteínas Morfogenéticas Óseas/genética , Factores de Crecimiento de Fibroblastos/genética , Perfilación de la Expresión Génica/métodos , Gentamicinas , Células Ciliadas Auditivas/patología , Trastornos de la Audición/genética , Trastornos de la Audición/patología , Receptores Notch/genética , Regeneración/genética , Transcriptoma , Proteínas Wnt/genética , Animales , Animales Recién Nacidos , Proteínas Morfogenéticas Óseas/metabolismo , Diferenciación Celular/genética , Proliferación Celular/genética , Pollos , Modelos Animales de Enfermedad , Factores de Crecimiento de Fibroblastos/metabolismo , Células Ciliadas Auditivas/metabolismo , Trastornos de la Audición/inducido químicamente , Trastornos de la Audición/metabolismo , Receptores Notch/metabolismo , Transducción de Señal/genética , Técnicas de Cultivo de Tejidos , Proteínas Wnt/metabolismo
17.
Biomed Res Int ; 2018: 5370802, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29850532

RESUMEN

Hereditary nonsyndromic hearing loss is extremely heterogeneous. Mutations in the POU class 4 transcription factor 3 (POU4F3) are known to cause autosomal dominant nonsyndromic hearing loss linked to the loci of DFNA15. In this study, we describe a pathogenic missense mutation in POU4F3 in a four-generation Chinese family (6126) with midfrequency, progressive, and postlingual autosomal dominant nonsyndromic hearing loss (ADNSHL). By combining targeted capture of 129 known deafness genes, next-generation sequencing, and bioinformatic analysis, we identified POU4F3 c.602T>C (p.Leu201Pro) as the disease-causing variant. This variant cosegregated with hearing loss in other family members but was not detected in 580 normal controls or the ExAC database and could be classified as a "pathogenic variant" according to the American College of Medical Genetics and Genomics guidelines. We conclude that POU4F3 c.602T>C (p.Leu201Pro) is related to midfrequency hearing loss in this family. Routine examination of POU4F3 is necessary for the genetic diagnosis of midfrequency hearing loss.


Asunto(s)
Pueblo Asiatico/genética , Pérdida Auditiva Sensorineural/genética , Proteínas de Homeodominio/genética , Mutación Missense/genética , Factor de Transcripción Brn-3C/genética , Adulto , Anciano , Secuencia de Aminoácidos , Secuencia de Bases , Preescolar , Análisis Mutacional de ADN , Familia , Femenino , Proteínas de Homeodominio/química , Humanos , Persona de Mediana Edad , Linaje , Factor de Transcripción Brn-3C/química
18.
Materials (Basel) ; 10(2)2017 Feb 04.
Artículo en Inglés | MEDLINE | ID: mdl-28772491

RESUMEN

First-principles calculations were employed to study the mechanical properties for the recently proposed tetragonal B4CO4 (t-B4CO4). The calculated structural parameters and elastic constants of t-B4CO4 are in excellent agreement with the previous results, indicating the reliability of the present calculations. The directional dependences of the Young's modulus and shear modulus for t-B4CO4 are deduced in detail, and the corresponding results suggest that the t-B4CO4 possesses a high degree of anisotropy. Based on the strain-stress method, the ideal tensile and shear strengths along the principal crystal directions are calculated, and the obtained results indicate that the shear mode along (001)[100] slip system dominates the plastic deformation of t-B4CO4, which can be ascribed to the breaking of the ionic B-O bonds. The weakest ideal shear strength of 27.5 GPa demonstrates that the t-B4CO4 compound is not a superhard material, but is indeed a hard material. Based on the atomic explanation that the ternary B-C-O compounds cannot acquire high ideal strength, we propose two possible routes to design superhard B-C-O compounds.

19.
Sci Rep ; 7(1): 15993, 2017 11 22.
Artículo en Inglés | MEDLINE | ID: mdl-29167473

RESUMEN

Design and synthesis of two-dimensional (2D) materials with robust intrinsic ferromagnetism is highly desirable due to their potential applications in spintronics devices. In this work, we identify a new 2D cobalt sulfide (Co2S2) material by using first-principles calculations and particle swarm optimization (PSO) global structure search. We show that the 2D Co2S2 is most stable in the litharge type tetragonal structure with space group of P4/nmm. The elastic constants, phonon spectrum, and molecular dynamics simulation confirm its mechanical, dynamical and thermal stability, respectively. It is also found that Co2S2 monolayer is a ferromagnetic metal with a Curie temperature up to 404 K. In addition, we propose a feasible procedure to synthesize the Co2S2 monolayer by chemically exfoliating from bulk TlCo2S2 phase.

20.
Materials (Basel) ; 9(7)2016 Jun 24.
Artículo en Inglés | MEDLINE | ID: mdl-28773636

RESUMEN

Motivated by a recently predicted structure of diamond-like BC2 with a high claimed hardness of 56 GPa (J. Phys. Chem. C2010, 114, 22688-22690), we focus on whether this tetragonal BC2 (t-BC2) is superhard or not in spite of such an ultrahigh theoretical hardness. The mechanical properties of t-BC2 were thus further extended by using the first principles in the framework of density functional theory. Our results suggest that the Young's and shear moduli of t-BC2 exhibit a high degree of anisotropy. For the weakest shear direction, t-BC2 undergoes an electronic instability and structural collapse upon a shear strain of about 0.11, with its theoretically ideal strength of only 36.2 GPa. Specifically, the plastic deformation under shear strain along the (110)[001] direction can be attributed to the breaking of d1 B-C bonds.

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